1. Field of the Invention
The present invention relates to a disk rotation device which rotates a disk, and a disk drive device which is provided with the disk rotation device to rotate the disk as the recording medium in the disk drive device.
2. Description of the Related Art
With the progress of the digital technique and the improvement of the data-compression technique in recent years, as the recording medium for recording information, such as music, animation, photography and illustration, the optical disks, such as CD (compact disk), and DVD (digital versatile disk) having the same disk diameter as that of CD and enabling recording the data in the quantity about 7 times that of CD, have become to attract the attention. With the low-pricing of the optical disk, the optical disk drive device in which recording data in the optical disk and reproducing of the data are carried out while the optical disk is rotated has come to spread.
The optical disk drive device is equipped with the main drive device and the tray. The main drive device includes the optical pickup which irradiates the laser beam to the optical disk, and the disk rotation device which rotates the optical disk in the rotation position. The tray is used when the optical disk is loaded to or ejected from the rotation position in the main drive device where the optical disk is rotated.
When recording the data in the optical disk, the optical disk is rotated by the disk rotation device, and the laser beam is irradiated from the optical pickup to the optical disk to form the mark region and the space region on the recording surface of the optical disk.
Moreover, when reproducing the data, the optical disk is rotated, the laser beam is irradiated from the optical pickup to the optical disk, and the reflected light from the recording surface of the optical disk is detected. At the time of recording and reproducing, the optical disk is rotated by the disk rotation device.
With the proliferation of use of the optical disks, the development of the optical disk drive device is activated and the rate of reading of the data from the optical disk is increasing. Generally, the method of increasing the rotational speed of the optical disk is adopted as the approach of increasing the rate of reading of the data.
Supposing that the reference rotational speed (which is equivalent to 200 rpm) of the early optical disk drive device is set to the 1× speed, the rotational speed higher than the 32× speed (which is equivalent to 6400 rpm) is commonly available to the recent optical disk drive device. Moreover, the latest version optical disk drive device can provide the rotational speed exceeding the 50× speed (which is equivalent to 10000 rpm) for the rotation of the optical disk.
By the way, if the rotational speed of the optical disk is increased, the optical disk drive device itself will come to vibrate. The vibration of the optical disk drive device itself becomes the factor of the vibration of the tray. Moreover, the rotation of the optical disk causes the air flow to arise with the disk rotation. At this time, the side walls of the reception portion of the tray will receive the force of the air flow directly. This also becomes the factor of the vibration of the tray.
As the rotational speed of the optical disk is increased, the frequency and amplitude of the vibration of the tray become large, and this becomes one of the main sources which cause the noise of the optical disk drive device.
When the rotational speed of the optical disk is below the 10× speed, the user is not so concerned with the noise of the optical disk drive device. However, when the rotational speed of the optical disk exceeds the 32× speed, the user may feel displeasure in the noise of the optical disk drive device.
Recently, the number of the users who are sensitive to sound has been increased, and the loudness which is generated by the optical disk drive device has become to affect the sales of the optical disk drive devices.
In order to reduce the noise, there is proposed an improved the optical disk drive device which is directed to improvement in the sealing characteristic of the open/close door which opens and closes the opening provided in the front face of the main body of the device for insertion and ejection of the optical disk, so that leakage of the sound made inside the main body of the device to the outside is suppressed (for example, see Japanese Laid-Open Patent Application No. 2000-231779).
However, since the optical disk drive device disclosed in Japanese Laid-Open Patent Application No. 2000-231779 makes use of the elastic force of the elastic member integrally molded with the door, the problem of deterioration of the durability of the elastic member may arise due to the secular change of the elastic member.
Moreover, when the rotational speed of the optical disk is further increased and the vibration of the optical disk drive device itself becomes still severer, there is a possibility that the acoustic isolation effectiveness become inadequate.